Driftmasters Pro and Lil Pro Rod Holder Bases are constructed of plated steel with a durable plastic coating to protect rods. Bases are aluminum. Stainless steel hardware included. Left thread model is for trolling off the port side of your boat and use hex nuts. Available: Pro Series 1 to 1-1/4 Square Rail Base. 1/2 threads. Pro Series Star Base - Left Thread. 1/2 threads. Pro Series 1-7/8 Clamp Mount Base. 1/2 threads. Pro Series Flush Mount Base. 1/2 threads. (not shown). Lil Pro Series 1 to 1-1/4 Square Rail Base. 3/8 threads. Lil Pro Series Flush Mount Base. 3/8 threads. (not shown). Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Mounting Bases.